[ECG made easy][conduction problems]

Answer 1

time taken SAN–>ventricles (normal = usually less than 220ms)

Answer 2

heart block

Answer 3

a delay of the conduction from SAN to ventricles at some point. Prolonged PR interval, still one P wave per QRS complex. Each wave IS conducted to the ventricles though.

Answer 4

failure of the SAN conduction to pass into AVN or His

Answer 5

As a distortion of the T wave - i.e. dont always look for a perfect well defined P wave.

Answer 6

Mobitz I
Mobitz II
x:1 conduction blocks

Answer 7

Progressive prolongation of the PR interval. Then failure of one P to result in QRS. Then it starts again with shorter PR intervals (which progress.. etc etc)

Answer 8

Normal PR and normal P and QRS. Then a single dropped QRS. Then it is normal again.

Answer 9

Alternate conducted and non-conducted atrial beats. The first ‘x’ is the number of atrial depolarisations which result in 1 ventricular depolarisation. (2:1, 3:1, 4:1)

Answer 10

Mobitz 1 = benign

Mobitz 2 & 2:1-4:1 blocks = indicative of future 3rd?

Answer 11

P standalone

P as a (regular) part of T

Answer 12

atrial contraction is normal
no P waves conducted to the ventricles
‘escape mechanism’ depolarisation of the ventricles

Answer 13

PR interval - no regularity

Answer 14

3rd degree

Answer 15

3rd degree heart block

Answer 16

less than 120 ms

Answer 17

Left (RBBB with normal QRS duration can be non-pathological)

Answer 18

RBBB (excitation spreads down the LBB and still depolarises the septum from L to R

Answer 19

V1 - R wave

V6 - Q wave (small!)

Answer 20

S wave - V1

R wave - V6

Answer 21

second R wave due to late RV depolarisation

Answer 22

R = septal depolarisation. +ve 
S = LV depolarisation (very deep due to mass) -ve
R1 = RV depolarisation (late due to RBBB) +v

(NB this is all in lead V1. Lead V6 would show very different things)

Answer 23

No - just QRS

Answer 24

partial RBBB (can be non-pathogenic)

Question 25

[conduction problems]: what would cause depolarisation of the septum from right to left

Answer 25

LBBB

Question 26

[conduction problems]: what the name and cause of the 1st wave be in leads V1 and V6 in LBBB

Answer 26

``` V1 = Q V6 = R ``` *small waves. R-->L septal depolarisation.*

Question 27

[conduction problems]: in LBBB what would be seen in relation to the T wave

Answer 27

Inversion in the lateral leads (VL, I, V5, V6)

Question 28

[conduction problems]: In RBBB why is the depolarisation of the RV very small and may not cause over the baseline deflection

Answer 28

small mass

Question 29

[conduction problems]: The patterns 'M' and 'W' would be seen in which leads and in which BBB

Answer 29

``` M = V6 W = V1 ``` LBBB (due to RV depolarising first in LBBB)

Question 30

[conduction problems]: how many divisions does the left BBB have

Answer 30

2 | posterior fascicle + anterior fascicle

Question 31

[conduction problems]: how many divisions does the RBBB have?

Answer 31

1 | called the RBBB

Question 32

[conduction problems]: what effect on the direction of the cardiac axis does left anterior fascicle block have

Answer 32

rotates upwards (the posteriori fascicle go under and up, remember)

Question 33

[conduction problems]: what is left anterior fascicle block aka?

Answer 33

left anterior hemi-block

Question 34

[conduction problems]: what causes left axis deviation? (2)

Answer 34

left anterior hemi-block or RBBB + left anterior BBB (bifascicular block)

Question 35

[conduction problems]: what happens to the cardiac axis if there if RBBB

Answer 35

nothing - stays largely the same. large mass of LV is the driving force in axis

Question 36

[conduction problems]: what causes right axis deviation

Answer 36

left posterior hemi-block | rarely selectively blocked however

Question 37

[conduction problems]: what is bifascicular block

Answer 37

LBB anterior fascicle block AND RBBB

Question 38

[conduction problems]: how do you differentiate between bifascicular block due to left anterior fascicle block + RBBB, and just LAFBBB

Answer 38

Check for left axis deviation then check for RBBB pattern (RSR1)